3.
a) (x²-10x+25)/(x²-25)=(x-5)²/(x-5)(x+5)=(x-5)/(x+5) B.
b) (-x²/y⁴):(-x⁴/y²)=(-x²/y⁴)×(-y²/x⁴)=1/(x²y²) B.
c) (2x+y)/(3x-y)=2/3
3(2x+y)=2(3x-y)
6x+3y=6x-2y /-6x
5y=0 =>y=0 C.
d) x=a²+a , y=a-1. ,z=a²-1
x×y/z=a(a+1)(a-1)/(a²-1)=a(a²-1)/(a²-1)=a B.
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